Carbon dioxide lasers are used in many commercial and military applications, including engraving, cutting, etc. Carbon dioxide lasers produce laser light in the infrared spectrum at around 10.6 μm wavelength. One variety of carbon dioxide lasers employ a ceramic bore which acts as an optical waveguide and/or a free space propagation path for the laser radiation and also confines the electrical discharge for exciting the carbon dioxide gas. Consistent with such a design, the bore must be provided as a very straight and accurately formed hole in the ceramic material with the outside of the ceramic body having electrical contacts and the ends of the bore being positioned adjacent to mirrors. The ceramic body may often be disposed in a metal enclosure, which may provide the necessary vacuum integrity, mirror supports, and seals.
The bore in the ceramic laser may be formed by drilling a hole in a unitary ceramic body, or may be formed as a groove in one ceramic body to which a covering ceramic body may be bonded using glazing or thermo-diffusion bonding techniques. In either instance, because the beam of light interacts to various degrees, depending on bore size, with the walls of the bore, the straightness and optical finish of the bore are critical to the performance of the laser. Care is, therefore, necessary in preparing the optical bore to ensure that there is not seepage or leakage of fritting material into the optical bore.
Mirrors, seals, etc. may be attached to the ceramic body to complete the laser. Features, such as mirrors, etc., which are provided in connection with openings in communication with the laser bore must provide a gas tight seal. A gas tight seal may be provided by various methods to make a seal to the ceramic. The mirror, or other feature, may be attached to the ceramic body by brazing or welding to a metallized ceramic surface, glass fritting directly to the ceramic, etc., to assure a gas tight seal.